3D stereoscopic displays show 3D stereoscopic images based on the principle of binocular parallax. That is, different images are respectively provided to viewer's left and right eyes such that 3D stereoscopic images can be synthesized from the left- and right-eye images. Commercial 3D stereoscopic displays can be largely classified into two types: a glasses type 3D stereoscopic display and a naked eye 3D stereoscopic display. The naked eye 3D stereoscopic display shows 3D stereoscopic images to the viewer without the need to wear any accessories. The naked eye 3D stereoscopic display can be largely classified into two types: a space-division multiplexing type and a time-division multiplexing type.
The naked eye 3D stereoscopic display of the space-division multiplexing type generates 3D stereoscopic images by separating the display image into left-eye image pixels and right-eye image pixels, and projecting the left-eye image pixels and the right-eye image pixels to the left eye and the right eye at the same time, respectively, by a split device. Then, the viewer can view a 3D stereoscopic image due to the effect of binocular parallax.
A liquid crystal (LC) lens can achieve the effect of the split device, by refracting left-eye image pixels to the left eye of the viewer, and at the same time refracting right-eye image pixels to the right eye of the viewer. In the operation of an LC lens, an electric field generated by at least one applied voltage is used to drive LC molecules to rotate in desired directions. In this way, regions with different refractive indexes are formed in the LC layer, thereby the focusing effects of a normal solid lens can be achieved so as to perform splitting. When the LC lens is not in operation, the 3D stereoscopic display can be switched to a 2D display. This allows the viewer to select to view 2D images or 3D stereoscopic images on the same display, and the effect of 2D/3D switching can be achieved.
Referring to FIG. 1, which is a schematic diagram showing a refractive index distribution curve of a conventional LC lens, when a high refractive effect is required, a gap d between a first substrate 11 and a second substrate 12 at two opposite sides of the LC unit must be largely increased as shown by the refractive index curve 10. This will increase the cost of the liquid crystal and the overall thickness of a completed display. Also, a too large gap will decrease the response speed of the liquid crystal. Therefore, a major object of the invention is to ameliorate the above-mentioned deficiencies.